The present invention relates generally to door hinges, and more particularly to gravity activated, self closing door hinges. Such hinges may be used in high traffic, restaurant kitchen swing doors requiring a full range of swing to both sides of the door frame, and in refrigerator doors requiring a range of motion to only one side of the door frame.
A typical gravity activated, self closing door hinge has a door jamb mounting structure and a pivot post for supporting a door panel. The hinge also has a complementary cam arrangement coupling the jamb mounting structure and the pivot post together in a manner which biases the door panel to a closed position. When closed, the weight of the door panel is transferred through the pivot post to the interface of the complementary cam faces to maintain contact between the cam faces. When the door is opened, an upper rotatable cam face slides across a lower fixed cam face, resulting in the upper cam, pivot post, and door panel being elevated above the closed position. When released from an open position, the weight of the door panel causes the upper cam to pivot and drop back to the stable lower position where the door is closed.
These earlier self closing hinges are exposed to potential abuse when mounted on doors in high traffic areas, and many designs cannot withstand this abuse. For example, U.S. Pat. No. 3,733,650 to Douglas teaches a lift-off gravity hinge mechanism with complementary cam members enclosed in a barrel member for use in exterior gate hinges rather than interior door hinges. When the Douglas hinge is opened, the hinge pin is elevated by the cooperating action of the cams. The Douglas hinge is dissembled by lifting the hinge pin out of the lower barrel. Thus, repeated jarrings by heavy objects passing through doors suspended by Douglas hinges may cause dislocation or even complete disassembly during service. This undesirable trait of Douglas represents at least a nuisance, if not a danger of injury.
Another self closing hinge is disclosed in U.S. Pat. No. 3,378,881 to Hentzi. Hentzi teaches a restaurant kitchen style gravity actuated pivot hinge with exposed complementary cam elements carried by a coaxial pivot pin. Upon rotation, the resultant cam action of the Hentzi hinge causes the upper cam to elevate. Under hostile conditions, the Hentzi hinge is vulnerable to damage due to the exposed nature of Hentzi's cam arrangement. The impact of a heavy object on the exposed cam could cause imbalance or damage the cam faces, resulting in a rapid degradation of the hinge. The closing speed of Hentzi's door may be too slow for some applications because the cam mechanism is the sole provider of the closing force.
The possibility of cam damage is minimized in the hinges of U.S. Pat. Nos. 4,631,777 to Takimoto, and 4,030,161 to Loikitz, which teach the shielding and sealing of the cam area. These hinges, however, are undesirable for use in a two way traffic door because they are not designed to enable a door panel to swing to both sides of a door frame. The Takimoto and Loikitz hinges apparently reach the closed position when the door panel contacts the door frame, and thus, neither provides for any closed door position adjustment.
Thus, a need exists for an improved gravity activated, self closing door hinge which is directed toward overcoming, and not susceptible to, the above limitations and disadvantages.